Shade Tree Mechanic's Guide to Final Drive Bearing Replacement

Discussion in 'GS Boxers' started by RockyRaccoon, May 28, 2007.

  1. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    * For R1100GS and R1150GS
    * Covers replacement of the tapered and ball bearings on the crown gear
    * Includes final drive seal replacement
    * Trailing arm pivot bearing replacement
    * Neutral indicator light switch replacement
    * Does NOT include R&R of the pinion bearings or seals


    The most important consideration for a shade tree mechanic is to find a nice shady place to work.

    If you're working on dirt, put down an old sheet of plywood or siding to keep things clean and to make it easier to find the nuts, screws and tools you'll drop.

    Shim one side of the centerstand as necessary to put the bike upright.

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    Secure the centerstand to the front wheel to avoid accidently tipping the bike forward off the stand. :uhoh

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    #1
  2. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

    Joined:
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    Oddometer:
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    Remove the brake caliper, ABS sensor (note the torx head on the sensor), the clamps holding the rubber boot to the final drive and trailing arm, and, if you still have it, the mud flap thingy.

    One of the allen heads on one of the small bolts holding my mud flap thingy promptly stripped out, but this was easily solved by driving a torx into the head, which turned it out nicely.

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    Use a zip tie or a garbage bag tie to hold the shims in place for the ABS sensor.

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    After you remove the wheel, drain the gear oil out of the final drive. Note the accumulation of dirt and grease on the lower edge of the seal, indication of a potential seal failure perhaps?

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    Then put blocks under the final drive to hold it up when you remove the shock.
    #2
  3. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

    Joined:
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    Oddometer:
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    Remove the rear shock.

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    And the preload knob.

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    #3
    Andrew likes this.
  4. Poolside

    Poolside Syndicated

    Joined:
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    <BR>You RULE man! This looks like it's gonna be GOOD<BR><BR>
    #4
  5. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Unbolt the rear brace bolt on the lower part of the final drive.

    If you have power and a heat gun, use them on the swingarm pin bolts to loosen the special heat-sensitive threadlock BMW uses. If you don't have power, you can use a propane torch...carefully to avoid marring the finish on your bike. Note that there are stories of people stripping the threads when they didn't use heat. Also note that if someone like me has done this job on your bike before you got it, it may have another type of threadlock that gets tighter with heat. So proceed with caution to remove the pin bolts on each side.

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    The final drive will then pull loose from the trailing arm.

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    You can pry out the rear part of the driveline with a long screwdriver. Just give it a snap.

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    #5
  6. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    If you're just working on the final drive, there is no need to remove the trailing arm.

    However, I took this opportunity to replace a balky neutral indicator light switch and replace the tapered roller bearings at the forward swing arm pivot.

    The front pivot bolts come out the same way as the rear ones, but you'll probably have to remove the left footpeg mount.

    The trailing arm will then slide out.

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    Be sure to prop up the driveline with a rag or something tucked between it and the lower part of the transmission housing.
    #6
  7. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    That round black thing in the middle of the picture with the wires coming out of it and the two small bolts holding it in place is the neutral indicator light switch.

    There are actually two pieces there. The neutral indicator is underneath the part you see, but it's held in place by the same two bolts.

    A very thin-sided 1/4-inch drive socket with a long extension comes in handy here. :deal

    When you pull it out, transmission grease will start running out of the hole, but if you work quickly, you won't lose more than a few teaspoons full.

    Be sure to get the O-ring and oil seal that go with the neutral indicator switch. The O-ring goes on the outside of the neutral switch and the seal inside it.

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    #7
  8. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Now to the trailing arm pivot bearings.

    Drive them out with a socket (1 inch worked for me) and a long extension or two.

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    Note: These are sealed bearings, and after 50,000 miles of dirt and water, they were still in good shape and probably didn't need to be replaced.


    Tap in the new ones. I'm using a plastic washer made for stuff like this. In the past I've used the back side of a socket with an extension put in backwards.

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    #8
  9. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Knock the pivot bearings out of the final drive the same way, but don't replace them until just before you are ready to put the drive back on the bike.

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    #9
  10. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Now you're ready to open the final drive.

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    Note that mine was clean as a whistle inside. If the bearing was failing, there would be chunks of metal, but mine was just worn, resulting in the play in the rear wheel.
    #10
  11. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    I used my special BMW final drive cover holding tool to secure the cover while I tapped out the crown gear.

    That other fancy tapper thingy came from Kragen.

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    #11
  12. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Inside the cover there's this spacer ring.

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    Next I pushed out the big final drive seal. This takes very little force, and installation is very easy as well. When you're ready (and we're not), just push it in.

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    #12
  13. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Next I pulled off the tapered roller bearing.

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    And the large ball bearing.

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    And the roller bearing race (after heating the housing with the heat gun). The race is supposed to fall out when the housing is heated, but it needed a little coaxing.

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    Note that I didn't have a very good puller for any of these jobs. It worked, but not gracefully. This little item came from Kragen.

    Also note that replacing the tapered roller bearing is optional and probably not necessary in most cases. These rarely fail.
    #13
  14. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    I froze the crown gear and the race for the tapered roller bearing.

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    I baked the large ball bearing and the tapered roller bearing at 250f for about 15 minutes.

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    And put them all together. The tapered roller needed a little persuasion. The big roller just dropped right on. Note that there's a spacer between the crown gear and the tapered roller bearing. Don't forget to put the spacer on before you put the bearing on. Also, make sure the beveled edge on the inside of the spacer ring is facing the crown gear.

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    I also heated the final drive housing with the heat gun and gently tapped in the frozen race.
    #14
  15. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Next I dropped the crown gear into the housing.


    (Note the garbage ties holding in the centers of pivot bearings, which I put in a few steps early.)

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    Here is where BMW says you need the real fancy special BMW tools to tell how thick your spacer ring should be. I just put the old one back in, figuring if it was done right at the factory the first time, it should still work.



    Anyway, I lightly lubed the big main seal and put it in the cover, put a new large O-ring around the cover, heated the whole thing in the oven to 175 f (to help it slide over the bearing), put in the big spacer ring and put the damn thing back together. The housing cover torques at 25.8 pounds.

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    #15
  16. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Reassembly is pretty straight-forward from here. The only tricky part is torquing the trailing arm pivot bolts. Put in the right side first and torque to 118 lbs, then the left side, which only goes to 7 lbs, then the lock nut torgues to 118 lbs. Be sure to use threadlock.

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    #16
  17. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Location:
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    Fill up the final drive with gear oil and take a short ride, say 20 - 50 miles, then change the gear oil just to clear out any gunk. :ricky
    #17
  18. RockyRaccoon

    RockyRaccoon Found:Gideon's Bible

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    Couldn't have done it without you and the pdf you sent. Thanks again! :wave
    #18
  19. GSposer

    GSposer poser

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    Location:
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    So.....when the final drive fails......it's just that big bearing??

    And you can do it without taking the whole assembly off the bike right?

    Looks doable on the road with the right tools and parts of course.....:evil

    BTW: Thanks!
    #19
  20. Poolside

    Poolside Syndicated

    Joined:
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    Location:
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    <BR>Shade tree repairs are the best. And double score for using wood for a tool :1drink


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    Do I spy a bearing cage there in the background? Did it not survive the pulling process?<BR><BR>
    #20